Remove remaining references to gray()

Author: vrugtehagel

completions/functions.py

@@ -111,7 +111,6 @@
     "fit-content": t.length + t.percentage,
     "format": [t.string],
     "frames": t.integer,
-    "gray": t.number + t.percentage,
     # "has": [],           # TODO: has takes a selector list as an arg. should it have completions?
     # "host": [],          # TODO: host takes a selector list as an arg. should it have completions?
     # "host-context": [],  # TODO: host-context takes a selector list as an arg. should it have completions?

completions/types.py

@@ -393,7 +393,6 @@
     device_gray,
     device_nchannel,
     device_rgb,
-    gray,
     green,
     h,
     hsl,